When there's sufficient demand and room for electricity to flow, utilities and grid overseers want wind farms to run full throttle. But during periods of congestion, or when market conditions call for less power on the grid, wind energy operators have to apply the brakes to keep their power from overwhelming the system. Such downward shifts in electrical output, called "curtailment," can make running a wind farm more difficult, especially when every turbine represents an independent engine that must be throttled up or down to meet the desired overall generation output. Curtailment remains one of the industry's most significant challenges as dozens of new wind farms come online every year.